Mac Software for Automatically Cleaning Out Duplicates in iTunes
This should be the part where I recommend some freeware on Mac for removing duplicates on iTunes. However, strictly speaking there is no freeware available for this purpose. Nevertheless, there is (paid or free-to-try) software available on mac that can help you get the job done. As removing duplicates should only be a once in a while procedure, a free-to-try option can get you a long way for free.
Rinse for Mac is software that can automatically perform certain maintenance tasks on your iTunes library. Not only can it find duplicates, it can also fix bad song information, add album art or organize genres. The trial period will only let you fix 50 songs however. The software is $39 to purchase.
IDupe has only one task and it is removing duplicates from your iTunes library. The application is considerably cheaper at $8 and will do a fantastic job at finding duplicates. A free trial version is available, which will evaluate your library. IDupe is probably the best option at the moment for finding duplicates in your iTunes library and is relatively inexpensive.
It may seem redundant to pay for software when iTunes by itself can find duplicates. Frankly, the built-in feature is not nearly as good as the paid alternatives and will use only few parameters for analyzing the library. Rinse and especially iDupe will do a much more thorough search and will come up with considerably better result. Depending on the size and the state of your library the choice is yours, but if the situation is really bad it might be worth to consider one of these alternatives.
Note. Did you find any good freeware that can clean iTunes from duplicates on Mac? Share it in the comment section!